A technique to evaluate the adequacy of human or machine translations is known. For example, a technique that evaluates speech translations by the pair comparison method using several automatic evaluations, which are called the BLEU, NIST and DP-based methods, is disclosed in the following Non Patent Literature 1.
[NPL1] Keiji Yasuda, Fumiaki Sugaya, Toshiyuki Takezawa, Seiichi Yamamoto, and Masuzo Yanagida, “Applications of automatic evaluation methods to measuring a capability of speech translation system,” In Proceedings of the 10th Conference of the European Chapter of the Association for Computational Linguistics (EACL 2003), April 2003, pages 371-378.